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Topic: Best component for project conceived (Read 801 times)

I'm a university student currently reading computer science. I've had this idea for a project, it's essentially an array of motors which need to move up and down (it will be programmed so that some of the motors move less or more than others) creating a 3D surface effect.

Here you can see an example, each of the grid squares would be an individual 'pin' which would (I assume) need to be driven by its own motor.

Although I have had a lot of programming experience, I have near to no robotics/electronics experience, so I was wondering if I could get some feedback and suggestions.

What would the best component be to use? Budget is an issue and if I used the cheapest motors I have seen (around £1.30 each) I would be looking at spening around £130 for a very very small prototype. I don't know if pistons or something are feasible; any ideas?

Thanks for taking the time to read through, feedback, as I say, would be greatly appriciated.

To be blunt... Either loose the force requirement (and probably the speed requirement), or get a different project idea.

The most compact solution I can think of is a ton of weak solenoids. These could be self-wound, I think, but I've never done such. They would still be a wiring nightmare that I couldn't tackle off-hand.

Do you really need each pin to deliver 20 N of force?The toy you showed looks like it has a pin density of about 100 pins per square inch. If you could achieve a pitch half of what they have you would have a pin density of 25 pins per square inch. At 20 N (4.5 lbf) per pin that would apply approximately 775 kPa (112 psi).

I like the idea of having pins that could screw in and out as it would provide some gear reduction. If you had 1" long pins with a #4-40 thread you would need a motor to turn at 12000 rpm to achieve a 0.2 s response time. Perhaps some of those little vibrating motors they use in cell phones would fit the bill.

Precise of the positioning of the pins will be challenging without a feedback mechanism. The pins could be zeroed to start but error will accumulate over time.

The pins could be hex or square in profile to keep them from rotating with a thread inside for a screw to move them in and out. Hex standoffs come to mind for a prototype anyways. I ran across this perforated sheet with hexagon holes http://www.mcmaster.com/#92725t42/=pokjde density may not be quite as high as you want tho.

Another idea is to use an electromagnet and return springs on each pin. The position could be controlled with the current. However the forces will likely be much lower than desired.

if each one of the pins is inside a tube you could use forced air or liquid to push them up. Just have one pump pumping and use electromagnets to stop/freeze the pins once they get to their desired location. The electromagnets would act as brakes pushing against the side of a pin to stop it. Very small speakers might work as these electromagnets. A cheap way to monitor the pin positions would be with two cameras, using computer vision to monitor their location in space. Don't forget the pins are two sided so you can hide the cameras in the back and if you color code the pins that are next to each other the cameras will have an easier time picking the same pin. Or you might just get away with timing but the air flow may not be regular enough. A cheap way to control the electromagnets would be using a grid of light sensing diodes ( mini photocells ) placed on top of an lcd monitor. You can than output using DirectX or OpenGL to the monitor, once a pin gets to its location draw a rectangle on the lcd where the light sensing diode is to stop the pin. On the next frame just stop the pump ( or have a valve diverting the flow ) and release the electromagnets and let gravity return the pins to their places, you might need springs if the pins are not facing up or the gravity is not strong enough to return them in time.

For the cameras you could use the ps3 eye they are very cheap now I saw some on clearance for 11$ recently. They have very high frame rate, but they are black and white so instead of color coding you may need to use shades of gray.